Operation of internal combustion engines of the compression ignition type



'ilnited States Patent OPERATION OF INTERNAL COMBUSTION EN- GINES OF THE COMPRESSION IGNITION TYPE Hebert D. Young, Hammond, Iud., assignor to Sinclair l.lsleiining Company, New York, N.Y., a corporation of awe No Drawing. Application August 13, 1951' Serial No. 241,705

4 Claims. (Cl. 123-1) My invention relates to a starting fluid for use in compression ignition engines which is particularly valuable in cold weather for low temperature starting.

It is well known that compression ignition engines employing regular diesel fuels are diflicult to start under conditions of low ambient temperature particularly at temperatures below about 32 F. In starting a cold engine, the temperature within the cylinder must be sufficiently high to ignite the regular fuel. Such temperatures are developed only after sufficient work has been done in compression of the charges within the working cylinder to bring the parts of the engine in direct heat exchange relation with the contents of the working cylinder, as well as the charge undergoing compression, to a relatively high temperature. Thus, at low ambient temperatures it is often difficult, if not impossible, to attain such required temperatures without special equipment and starting methods.

With the widespread use of diesel engines, particularly in mobile auto-powered equipment in the transportation and construction fields, cold weather starting difiiculties for such engines often involve serious economic loss above the mere delay in use of the automotive equipment, hence considerable time and attention have been given to the problem of obtaining reliable and inexpensive cold weather starting methods. Such methods employ Winterizing techniques and mechanical starting aids, for example, combustion type air induction heaters, external heaters for engine jacket coolants, jacketed crankcases and the like.

One such method for starting of compression ignition engines contemplates the use of an auxiliary fuel, a starting fluid, in combination with the regular, primary fuel. The auxiliary fluid is aspirated with the engine air intake during starting until combustion of the regular injected fuel is continuous.

I have discovered that volatile organic nitrates, particularly alkyl nitrates, e.g. amyl nitrate, possess specially desirable properties which render them useful aids in cold weather starting of diesels. I have also discovered that blends of amyl nitrate and diethyl ether possess additional extremely useful properties highly desirable in diesel starter fluids. My invention provides a starting fluid containing about 5-95 by volume of diethyl ether and about 95-5 by volume of amyl nitrate. I prefer compositions within the approximate range of about 5- 50% by volume of diethyl ether and about 95-50% by volume of amyl nitrate. I particularly prefer a composition of about 20% diethyl ether and 80% amyl nitrate (parts by volume).

In evaluating the relative effectiveness of a given diesel fuel one of the primary criteria of low temperature starting is the minimum compression ratio required for starting the engine. Thus, using the same engine and the same jacket and air temperatures, different fuels may be conveniently evaluated in the laboratory for their cold weather starting performance by comparison of this critical compression ratio. The test is referred to as CCRD test (critical compression ratio differential). The CCRD data have been previously correlated with actual cold weather experiments and have been demonstrated to provide accurate relative prediction of cold weather starting. Such data are to be preferred to actual cold tests as they are more economical and more readily obtained. Where herein referred to, the CCRD data were derived under the following conditions using a CFR Waukesha diesel test unit (1937):

Jacket temperature 30 F. Air intake temperature 38 F. Primary fuel injection rate 13 cc. per minute.

To evaluate the starting characteristics and effectiveness of secondary fuel aspirated with the air intake, the further test conditions were employed.

Primary fuel used 50 cetane number Mid Continent diesel fuel. Quantity secondary fuel aspirated per trial 5 cc.

The engine was constantly motored at 900 r.p.m. under equilibrium conditions. The initial compression ratio for the engine was set below the point at which ignition of the primary fuel occurred for an injection duration of 10 seconds. From this point the compression ratio was gradually raised at 10 second intervals until the critical compression ratio of the primary fuel was reached, as

evidenced by continuous combustion of the fuel. When this value was determined by three separate determinations, the compression ratio was again substantially lowered and the critical ratio of the primary fuel plus aspirated secondary fuel was determined in like manner. The difference between the two values represents the critical compression ratio difference (CCRD) of the secondary fuel.

Under these test conditions the CCRD data were determined using as starting fluids diethyl ether, a proven and well known auxiliary starting fluid, amyl nitrate, and a blend of amyl nitrate and diethyl ether in a 4:1 volume ratio. The following table illustrates the results:

(vol.) Amyl Am nitrate, Diethyl nitrate 20% (vol.) Ether Diothyl Ether CCRD value 3. 75 5. 50 4. 40 Getaue number 275 Boiling range, F 305 100-305 94 Pour Point, F l39 146 176 Vapor Press. at 100 F., p.s.i.a 0.16 5. 7 16. 7

As the above table shows, amyl nitrate is almost as effective a secondary fuel as diethyl ether, having a CCRD value close to that for diethyl ether. However, amyl nitrate is not as useful in extremely cold weather since it has low volatility. The blend of amyl nitrate and diethyl ether illustrated, however, surmounts these Amyl Diethyl Nitrate, Ether, CORD vol. .vol. Value Percent Percent .100 3.75 90 10 6. '25 so 20 5.50 70 30 5.30 60 40 5.30 50 50 5.25 40 v60 5.25 20 t so 5.25 0 100 4.40

Thus, the improvement exists over an .extended'range within the approximate limits of about %95% by volume of diethyl ether and about 95%-5% by volume of amyl nitrate. Moreover, within the range of about 5%- 50% by volume of diethyl ether and about 95%-50% by volume of amyl nitrate, the blendsare not subject to the usual disadvantages of diethyl ether. Burning is smooth anddetonation difiiculties are overcome. In all blends the volatilities were sufficient for aspiration with the air intake under severely cold weather conditions, yet such volatilities were insufllcient to amount to a hazardous problem in warm weather and consequently the blended fluids may be conveniently stored and handled.

The manner in which starting fluids are best used is known to the art. For details and different suggested methods of aspiration I make reference here to my copending application Serial No. 84,733, filed March 31, 1949, for Diesel Starting Fluid,'now Us. Letters Patent No. 2,575,543, issued November 20, 1951.

I claim:

1. In the operation of internal combustion engines of the compression ignition type, the improvement which comprises burning a primary fuel while introducing with the air supply an auxiliary fuel consisting essentially of about 5% to 95% by volume of diethyl ether and about 95% to 5% by volume of amyl nitrate.

2. In the operation of internal combustion engines of the compression ignition type, the improvement which comprises burning a primary fuel while introducing with the'air supply an auxiliary fuel consisting'essentially of about 5% to by volume of diethyl ether and about 95% to 50% by volume of amyl nitrate. 7

3. In the operation of internal combustion engines of the compression ignition type, the improvement which comprises burning a primary fuel while introducing with the air'supply an auxiliary fuel consisting'essentially of about 20% by volume ofdiethyl ether and about by volume of amyl nitrate. I l

4. In the operation of internal combustion engines of the compression ignition type, the improvement which comprises burning a primary vfuel while introducing with the air supply an auxiliary fuel consisting essentially of to 50% by volume of diethyl ether and about 5% to 50% by volume of amyl nitrate.

References Cited in the file of this patent V OTHER REFERENCES LangsHandbook of Chemistry? 4th ed. 1941 p. 286, Handbook Publishers lne, ,Sandusky, Ohio. 

1. IN THE OPERATION OF INTERNAL COMBUSTION ENGINES OF THE COMPRESSION IGNTION TYPE, THE IMPROVEMENT WHICH COMPRISES BURNING A PRIMARY FUEL WHILE INTRODUCING WITH THE AIR SUPPLY AN AUXILLIARY FUEL CONSISTING ESSENTIALLY OF ABOUT 5% TO 95% BY VOLUME OF DIETHYL ETHER AND ABOUT 95% TO 5% BY VOLUME OF AMYL NITRATE. 